1. Field of the Invention
The present invention relates to a circuit breaker, and particularly, to a vacuum interrupter for a vacuum breaker which can improve circuit breaking function by making an electrode structure as a vertical magnetic field method.
2. Description of the Background Art
Generally, a circuit breaker is a electric protecting apparatus which is installed between an electric source and load units in order to protect a load unit and a load line such as a motor, and a transformer from an abnormal current(a large-current caused by accidents such as short circuit and a grounding fault) generated on an electric circuit such as a transmission/distribution line and a transforming device for private, to opening/closing load circuits, and to perform distribution function for changing the electric power line to another line.
In addition, the circuit breaker can be classified into an oil circuit breaker using oil, a gas circuit breaker using SF6 gas which is inert gas, an air circuit breaker using the air, a magnetic blow-out circuit breaker using magnetism, and a vacuum breaker using vacuum in accordance with used arc extinguishing medium.
Herein, the vacuum breaker has higher insulating strength in a vacuum state of 10xe2x88x923 torr, and therefore it is used most frequently among middle voltage circuit breakers. In addition, developments for high voltage, large current, and for small size are proceeded.
A vacuum interrupter which is a major constitutional component of the vacuum circuit breaker is provided to break the electric current by separating a movable electrode and a stationary electrode, if a mechanical actuator is operated by an electric signal of the abnormal current which is detected in a controlling circuit when the abnormal current generated.
The vacuum interrupter for breaking large current can be classified into a horizontal magnetic field type and a vertical magnetic field type. In case of the horizontal magnetic field type vacuum interrupter, an arc is extinguished while moving an arc magnetic field generated horizontally in accordance with the arc which is generated naturally in vertical direction when the contacts are separated. However, in this vacuum interrupter of horizontal magnetic field, the arc is concentrated on one point on the contacts when large current of higher than 40KA is generated, and therefore the contacts may be melted by the concentrated arc. In addition, a fusion line is formed on the contacts along with the moving path of the concentrated arc.
Therefore, in order to solve the problems of the vacuum interrupter of horizontal magnetic field, there was provided a vacuum interrupter of vertical magnetic field form as U.S. Pat. No. 6,163,002 by the patentee of the present invention. In the vacuum interrupter of the above patent, three or four magnetic fields are formed using movable electrode and stationary electrode which form three or four electric current loops, and therefore the arc is not concentrated on the contact. However, it is effective in case that the arc is generated in the three or four vertical magnetic fields, but the only one or two arcs can be generated and these may be generated on boundary portion between the vertical magnetic fields. Therefore, it is difficult to deal with the one or two arcs which are concentrately generated with the three or four vertical magnetic fields, and the arc dispersion operation is not performed for the arc which is generated on the boundary between the vertical magnetic fields. Therefore, the problems of the conventional art such as a surface concretion on the contact can not be solved.
Therefore, an object of the present invention is to provide a vacuum interrupter for a vacuum circuit breaker by which an arc is rapidly extinguished and a melting phenomenon of a contact can be prevented when a large abnormal current is broken by forming one magnetic field affecting evenly to entire surface of the contact in vertical direction parallelly with the arc when an electrode is separated.
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a vacuum interrupter for a vacuum circuit breaker comprising: a vacuum container which is sealed so as to be vacuum state therein; a stationary cylinder electrode fixed on upper part of the vacuum container so as to be sealed and connected to electric source; a stationary disc electrode, in which a plurality of slits extended from positions dividing an outer circumferential surface into three parts as predetermined angles towards positions eccentric as predetermined angles from center, connected to the stationary cylinder electrode mechanically and electrically inside the vacuum container, and a plurality of electric paths formed by the slits in order to form a vertical magnetic field are included.
In addition, there is provided a vacuum interrupter for a vacuum circuit breaker comprising: a stationary contact plate connected to the stationary disc electrode; a first shielding plate installed between the stationary disc electrode and the stationary contact plate in order to break the stationary disc electrode and the stationary contact plate electrically and magnetically; a plurality of first conductive pins installed on outer side of the shielding plate between the stationary disc electrode and the stationary contact plate in order to connect the stationary disc electrode and the stationary contact plate electrically; a movable contact plate installed so as to face the stationary contact plate and movable between positions of contacting to the stationary contact plate and separating from the stationary contact plate; a movable disc electrode connected to the movable contact plate electrically, wherein a plurality of slits extended from positions dividing the outer circumferential surface into three parts as predetermined angle toward the positions of eccentric from the center as predetermined angle are included, and a plurality of electric paths formed by the slits in order to form one vertical magnetic field by compounding a magnetic field formed by the stationary disc electrode and a magnetic field formed by a plurality of electric paths of electric current flowing to same direction as the electric current flowing on the electric path of the disc electrode are included; a second shielding plate installed between the movable disc electrode and the movable contact plate for shielding the stationary disc electrode and the stationary contact plate electrically and magnetically; a plurality of second conductive pins installed on outer side than the shielding plate between the movable disc electrode and the movable contact plate in order to connect the stationary disc electrode and the stationary contact plate electrically; and a movable cylinder electrode connected to the movable disc electrode electrically and mechanically, connected to electric load, and installed on lower part of the vacuum container so as to be sealed.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.